Graphitized porous carbon microspheres/paraffin composite phase change materials were prepared which could be used for the thermal management. KOH was introduced to help carbon microspheres to form the porous structure. The porous carbon microspheres exhibited good sphericity, abundant pores and large surface area, which would be more convenient to absorb the paraffin. The porous carbon microspheres were treated under different temperatures using Fe(NO3)3 as catalyst to investigate the degree of graphitization. The graphitization temperature played an important role in improving the thermal conductivity of the phase change composite.